- Samples must be sent for local institution and COG Reference Laboratory studies NOTE: *It is urged that a bone marrow aspiration be performed for every patient with suspected ALL. However, a marrow is not required for patients with ≥ 100,000/μl peripheral blood WBC and ≥ 75% blasts or for those patients whose clinical condition precludes performing the procedure safely. Patients with a medical contraindication to the procedure must be discussed with one of the study coordinators and must have a peripheral blood WBC of ≥ 30,000/μl with ≥ 75% blasts.